Instrument construction



Feb. 5, 1925. 1,525,253 H. SCHLAICH INSTRUMENT CONSTRUCTI ON I Filed April p25, 1915 Fatented Feb. 3, i925'.

tarea narran rar .arr erica.

HERMAN SCHLAICH, OFBROQKLYN, NEW YORK.

INSTRUMENT CONSTRUCTION.

Application filed April 28, 1919. Serial No. 293,265.

Stateof New York, have invented certainAV new and useful Improvements in Instrument Constructions, of which the following is a specification.

rl`his invention relates to the construction of instruments, particularly indicating instruments, such as thermometers-gages, clocks and the like, and comprises certain improvements in instrument casings, in bearings for shafts and arbors or other rotatable members used therein and in varions details relating especially' to the manner of mounting and connecting the tubular members utilized in thermometer or gage constructions ot' the Bourdon spring type.

Certain types of instruments, such as the tempe ature indicating instruments utilized for indicating the thermal condition of internal combustion motors or airplanes or other motor vehicles are subjected to severe and continuous vibration which tends to loosen screws and disconnect'other fastening means utilized in such .instruments and particularly in the casings thereof and it an important object of the present invention to provide an improved casing construction for an instrument adapted 'to be used under such severe conditions in which fastening means are employed of such character that they cannot becomed loosened or disconnected by vibration. In the preferred application of my invention I provide an invl strument casing in which no screws whatever are utilized in securing theV various parts together. Also I provide a construction which is very economical to manufacture, which may be assembled with great ease and which may be readily taken apart whenever' it is desired to inspect or repair the operative parts of the instrument. At thc same time the parts are secured together in such a firm and substantial manner as Ato be immune from the effects of vibration. \Vhile this hform of casing finds especial utility in instruments subjected to severe vibration it is obviously also of value in connection with instruments-used in any manner, because of its simple construction and the ease with which it may be assembled and disassembled.

Another object of the invention is to provide an improved bearing construction also especially applicable to instruments subjected to severe vibration but capable of use in various forms of instruments. Additional objects of the invention will appear in connection with the description of one specific embodiment of my invention which I have chosen vto illustrate the principle thereof. p

vIn the accompanying drawings,

Figure l is a sectional View taken on line I-I of Figure 2 illustrating my improvements as embodied in a distance type thermometer of the character employed for indicating the thermal 'condition of aeroplane or other engines.

Figure 2 is a transverse sectional view of the instrument shown in Figure l taken on line II-II of Figure l..

Figure 3 is a perspective view of the casing back, dial supporting arms and dial.

Figure 4 is a detail sectional View on an enlarged scale of the supporting post for the Bourdon spring, taken on line IV of f Figure 2.

Figures 5 and 6 are detail sectional Views showing intermediate steps in the process of c'onnecting the front and rear portions of the outer casing.

Figure 7 is a detail plan View of a portion of the back-plate of the instrument casing showing the attachment of the leadingin sleeve thereto. Y v

` Referring to the drawings in detail and first t0 the casing construction illustrated,

the casing comprises a rear outer shell member l, preferably of cylindrical form and having Aits front edge turned outwardly to form a flange 2 which is, preferably provided with a beveled edge as shown at 3. Alfront casing member 4 is provided which has an outwardly turned flange 5 adapted to rest against the flange 2 and to be secured thereto by having a lip 6 bent over at the periphery of the fiange. so as to engage beneath the beveled edge 3 of the flange 2. In the manufacture'of this construction, the lip 6 is preferably formed at right angles to the Hangs, as shown in Figure 5, and the flange 2 then brought against the flange 5 after which the lip 6 is bent or "spun over the beveled edge 3 as shown in Figure 6. The projecting portion of the lip 6 is then faced olf flush with the under surfaceof the flange 2 thereby providing a smooth faced collar or rim projecting outwardly from the casing and adapted to be seated upon `and attached to the instrument board 7 or other support. The front of the instrument is preferably closed by a cover glass 10 which may-be secured in position in any'suitable manner as by means of a bezel 11 screwing on a screw threaded portion 12 of the casing member 4, a washer or packing 13 of parallined paper or other suitable composition being inserted between the bezel and glass. The'back of the instrument casing which also preferably constitutes a base for. supporting the working parts thereof, comprises a plate 15, which kis preferably formed with an 1ntegral flange 16 adapted to iit Within the rear .edge of the casing member 1. A plurality yof spring arms 17 are also provided, (three in the particularconstruction illustrated), these arms being preferably formed integral with the back plate and its 'flange and being arranged to tit 4snugly within the casing member 1. These arms and the casing member are suitablyformed to interlock so as to hold the back-plate and casing member together.

The construction shown for this purpose comprises a stud 18 on each of the arms- 4 adapted 'to be received in a corresponding `each of the arms.

hole 19 formed in the casing wall. Owing tot the resiliency of the -arms 17 they may be sprung inwardly suiiciently to permit the studs to pass inside of the casing wall until the holes 19 are reachedwhen the studs sna into the holes and so lock the back plate an casing together.

The arms 17 in addition to securing the back-plate4 and casing member together are also preferably employed to oarr the front'` plate or d ial ofthe instrument. uch al dial plate is shown in the drawings at 20 and comprises a metal disc notched as indicated at 21 to receive the upper ends of the arms V17. Projecting from the bottom of each notch is a tongue portion 22, adapted to project through a slot near the outer end of Before the arms are. inserted within the casing member 1, they are sprung apart sufficiently to permit the tongues 22 to be engaged within the corresponding slots'after which the dial and arms are introduced into the casing member and the studs 18 engaged within the holes 19. When this has been accomplished it will be seen that the parts of the instrument casing includin the dial are fully assembled and securely ocked together without the use of screws or other removable fastening devices.

interrate The dial plate acts as a support for the outer ends of the arms and holds them firmly in engagement with the inner walls of the casing member. At the, same time the engagement of the' arms with the latter prevents them from lsepa-rating, and so retains the arms in positive engagement With the dial plate. l

To remove the back-plate and dial from the casing members it is merely necessary to -force inthe studs 18 sufficiently to permit them to clear thewalls of the holes 19 in the casing member when the parts may be readily drawn apart. A suitable tool adapted to apply pressure to thethree studs 18 simultaneously may be provided for this purpose ifdesired.

In a construction such as that illustrated in which the front casing member 4 is of smaller diameter than the rear casing member 1 and in which the dial platefits within the front casing member, the arms are inwardly offset near the extremities as indicated at 23.

rllhe -ivorks of the instrument are located between the back-plate and the dial plate,

and are `preferably varranged'so as to be chiefly carried by the back-plate 15. In the thermometer or gage construction illustrated, an index hand is provided which is adapted to be moved over the front of the dial plate and to be visible through the glass crystalof the instrument. This indicating hand is shown 'at 25 in Figure 1 and is fixed to the outer end of the journal 26 projecting from the arbor 27 ymounted within the instrument. The arbor 27 has a second journal 28 projecting from its opposite end, both of these 'journals being of smaller diameter than the arbor itself. The bearings '29 and 30 for these journals are preferably mounted i respectively upon` th dial plate 20 andthe back plate 15, and may be secured in position in any suitable manner but preferably they are each formed with a neck-31 of re-V duced diameter adapted to bereceived Within a hole in the.plate carrying 4the same, the outer end of the neck being riveted over slightly. Each of the bearings has a fbore 32 of a diameter to form a"close,-b`ut not tight fit-with the corresponding journal portion of the arbor, so that these journals will Y of., I preferably form in the vbearings thev is Supported in position only by the engagement of the journals 2(3ancl 28 in the bores 32 in the bearings, thus securing the advantage ot' the very small frictional resistance resulting from the small diameter of'the journals. but in case of the breakage 'of' a journal. then the end ot the arbor will be supported by its engagement with the Walls ot' the bore 33, so that the arbor is still Sustained .in its proper position.

The arbor 2 7 may be readily assembled within itsl bearingsat the time that the dial plate is introduced between the ends of the arms 1T, the locking ot' the dial'plate in position asabove explained also retaining` the' arbor in its bearings.

l `he working parts ot the instrument illustrated, are of the same character and opgrate in the saine manner as that described in my application for United States patent, Serial No. 218,801, filed February 29). 1918. The niain operative element comprisesa. Bourdon spring or flattened tube coiled into a double helical coil and supported at one end by tached to the back plate. The free end of the Bourdon spring or tube is connected to the end ot the longer arm of a lever member 2&6 mounted to rotate freely on the arbor 27 and haring its lshort arm connected at 38 to the rear end of'a bimetallic compensating coil 39, the forward end of which is fastened to the arbor at the point 40. The support for the fixed end otthe Bourdon coil preferably comprises a block or stud secured to the back-plate 15 in any suitable manner,

. as by having a neck 46 fitting a hole in said back plate and riveted over, this studbeing biturcatedas indicated at 47 so as to receive' the end of the flattened Bourdon tube 0r coil 35.

tions are to be given of changes in tempera` ture occurring at a distant point, a bulb 50 is provided which is to be located at. the distant point and which is connected tothe Bourdon coil by a tube 51, the coil, tube and bulb being preferably filled with an ex pansible liquid such as alcohol, glycerine or a suitable support at-` Preferably the hole leit?) which 'receives the neckl is notched out so as to mercury. The tube 51 is preferably ofv very small bore and as illustrated is 0i the star :shaped configuration'described in my application for patent above-referred to and is preferably connected with the end of the 'Bourdon tube byibeing inserted a little lway within the latter and secured by solder. For the purpose of introducing the expansible liquid into the system a short section ot' small tube 52 is prefierablyeemployed, the end of which is also introduced into the end of the flattened Bourdon tube. The

latter is preferabl .opened up at two points into a sort of igure 8 shape as Yshown in Figure 4. the ends of'the tubes 51 and 52 being introducedinto-the opened up por# tions of the Bourdon tube and bcng'sealed therein by solder which is also filled into the notch 47 of' the block 15 as indicated at 53 so as to'hold the tubes securely in the notch. This construction is one which may be very readily assembled-and in which the parts are lirmly secured together without dangercf leakage.- 'When the tubes and bulb have been properly filled with liquid through the tube 52 the end of' the latter is' sealed by Welding or soldering.

The tube 51 is preferablyvv enclosed throughout that portion of its length eX- terior to the instrument casing by a jacket tube 55, as described iii-my afo'rcsaii'l application for patent. this jacket tube tending ,to prevent injury to the capillary tube '51 and also insulating the capillary tube to a certain extent against'. the effectsot external temperature changes. Further protection againstbreakage ol the capillary tube may loo" also be.. provided in the forni of a flexible f tubular armour 5G which may be extended to enclose a part or all of theitube 55. 1`he capillary tube is preferably introdiicectinto the casing through a sleeve 60 attached to the back-plate of the casing, this sleeijc (50 being conveniently mounted by havingla reduced neck portion Gl projecting through a hole (32 in the back-plate. This hole iS preferably formed with the notched corners 63 so as to give it a. generally rectangular form as is shown in Figure .7. portions of the neck 61 being riveted "over 4into the notches 63. The sleeve GO is thus secured to the plate and at the same' time positivelylield against rotation with relation thereto. The

' sleeve has an opening through the inner end thereof indicated at 65. ot such diameter 'that the end of the casing tube 55will fit the same. closely. the latter being pre'l'erabl)Y hanged over the end ot the sleeve inside of the casing and secured by solder as indicated at 66. The capillary tube is continued over to the block 45 as already described. yThe casing 60 is preferably provided with (STof suflicient diameter to receive the end of the tulnilar'arniour 5G which may be-secured in such bore by solder. The construcizo a bore tion described provides a simple and readily assembled, and at the same time firm mounting for the ends of the casing tube and tubular armour which is particularly important in an instrument subjected to severe 1,- Vibration as it etfectually prevents breakage of the capillary tube where it enters the casing, this being one ofthe most frequent causes ot' trouble in an instrument of this vcharacter unless proper precautions are taken to avoid thedifHcult-y.

WhileI have Aillustrated and described one construction'of instrument embodying the various features'of my invention in pre,- .'t'erred form, it will be understood that I do not intend to limit myseltl to the specific embodiment shown but that I intend` by the appended claims tov cover my invention broadly in whatever form its principle may '20 he employed. It will also be understod that all of the different novel features described need not be employed in a single construction but that such features may be utilized individually where desirable. Y

Having thus described my invention, I claim:

l. In ihstrument construction the combination of a casing comprising a shell` a back plate forA the casing having arms extending forwardly within the casing shell, a dial plate carried by said arms, bearings on said dial plate and back plate, and an arbor journaled in said bearings, said dial. plate` casing and arms being so constructed that the dial plate is removable from said arms when the back plate is removed from the casing but is locked in engagement with said arms when the casing shell and back plate are in assembled relation.

2. In instrument construction the combination of a casing comprising a shell, asheet metal back plate having forwardly bent arms, a dial carried by said arms, a rotatable f arbor supported by said dial and back plate,

i and a helically coiled Bourdon tube supported at one end upon said back plate and having its other end operatively connected with said arbor.

3. In instrument construction the combination of a casing shell, a back plate, a front plate, means for connecting said plates to one another, said means comprising tongues projecting outwardly1 from recesses in the edge ot' one ot the plates, and resilient' arms in-A 455 tegral with the other plate and having recesses for receiving 'said tongue, said arms being pressed against said plate by engagement of the casing shell therewith;

4. In instrumentconstructi'on the combination of a casing shell, a sheet metal back plate having integral arms ve.\:tending for` wardly within the casing shell,` said arms being resilient and in frictional engagement with the wall of the casing shell, a dial plate carried by said arms, bearings carried' by bled.

Y1,525,253 L y when the front plate, arms and back plate are assembled with the easing.

(i, In instrument construction the combination ofa casing shell, a back plate, a front plate, one ot' said plates being provided with spring arms engaging with and supporting the second platsaid arms being infiim engage-ment 'with the wall of the casing shell and being pressed inwardly thereby into firm engagement with said plate.

47. In' instrument construction the combination of a casing comprising a shell, a back plate, and a front plate, one of said plates being provided with spring arms adapt-ed to `engage and support the second plate, said,

enga-gement being maintained by pressure of the casing shell against the arms when the plates and-arms are assembled with the casing shell.

8. In-instrument construction the combination of a casing comprising a shell, a front plate. and a back plate, one of said plates being provided with arms adapted to fitwithin the casing shell and having means at their ends for engaging and supporting the other plate, said means being held in engagement with said plate when the parts are assembled, by the engagement of the casing shell Walls With'rsaid arms.

9., In' instrument construction the combination of a casing comprising a. shell, a back plate having integral forwardly projecting arms provided with` slots near their ends, said arms being adapted to fit closely Within the casing shell, and a tro-nt plate. carried by said arms and having portions adapted to project into said slots, said arms being held in engage-ment with said front plate by the engagement of the casing shell Walls therewith when the parts are assemv10, In instrument construction the combinat-ion of a casing comprising a shell; a back plate having mounted xthereon the operative parts 'of the instrument, and a snap connection for connecting said back plate to said casing shell. A

l1. In instrument construction the conibination lof a casing shell and a back plate therefor having a yielding spring portion iitting within the casing shell, said casing shell and yielding portion having interlocking parts adapted to snap into locking engagement when the back plate is brought into assembled relation lwith the casingA shell. 13o

within said cylindrical casing portion, said arms havmg projections adapted to snap into said holes so as to hold said casing vmember and back plate member together.

14. In instrument construction the combination of a cylindrical casing' member having spaced holes therein and a back plate member having yielding arms adapted to fit Within said cylindrical casing portion, said arms having projections adapted. to snap.

into said holes so as to hold said casing member and back plate member together, and a front plate carried by said arms.,

15. In instrument construction the com bination of a cylindrical casing member having spaced holes therein, a back plate member having yielding arms adapted to -fit Within said cylindrical casing portion, said arms having projections adapted .to snap into said holes so as to hold said casing memberV and back plate member together,-

a front plate carried by said arms, an arbor journalled in bearings in said back and front plates, andl a helically coiled Bourdon tube mounted between said'back and front plates and operatively connected ywith said arbor.

16. In instrument construction the combination of a casing comprising a back plate, a front plate, a helically coiled Bourdon tube mounted between said back and front plates and supported at one end by said back plate, an arbor to which the free end of said Bourdon tube is operatively connected, said arbor having a journal portion of reduced diameter at each end thereof, `and bearings forsaid arbor in said back and front plates respectively, each of said bearings having a bore of small diameter adapted to receive the corresponding journal portion of .said arbor and a bore of larger diameter adapted to'receive the adjacent end portion of the arbor, said last mentioned bore being of sufcient diameter to provide a clearance between its inner surface and the adjacent surface of the arbor.

17. In instrument construction the combination of an arbor having a journal portion of reduced diameter, and a bearing for said arbor having a bore of small diameter adapted to fit said journal portion anda bore of larger diameter adapted to receive the adjacent end portion of the arbor but sufliciently larger than the diameter of the latter so that the end portion lof the arbor shall normally'be out of frictional contact with the walls of' said second bore.

18. In instrument construction, a casing member coniprising two concentric cylindrical portions provided With adjacent outwardly turned flanges interlocked together so as to unite said casing portions and provide 'an outivardly extending attaching flange'between the ends of the instrument casing for attaching said casing to an instrument board or the like.

19. Infi'nstrument construction, a casing member comprising tivo concentric cylindri- Vcal portions provided With adjacent outwardly turned flanges, one of said flanges having a beveled edge and the edge of the other flange .being turned over and interlocked beneath said beveled edge and faced oli' flush'withrthe surface of said second flange so as to provide a flat faced attaching flange for the instrument.

20. In instrument construction the combination of a casing provided With a back plate having an irregular hole therein, a notched stud having a reduced neck portion fitting said hole and having its outer end riveted over to secure said stud to said back plate, and a Bourdon spring Within said casing having one end secured Within the notch in said stud.

21. In instrument Construction the com' bination of a casing back having a round 1 hole therein notched out at intervals, a notched stud having a neck portion of reduced 'diameter fitting said hole and riveted over yso as to have. portions of' the metal forced into the notches of the hole in the back plate and thereby secure the stud rigidly to the back plate and hold the same against rotationlwith relation thereto, and a Bourdon coil having one end secured Within the notch in said stud.

22. In instrument construction the combination of a supporting plate having a round hole therein notched out at intervals, and a member having a cylindrical neck portion fitting said hole and having the metal thereof upset adjacent to said notched out portions so ast-o attach said member to saidv supporting plate and prevent rotation of said member With respect to said plate.

23. In instrument construction the combination of a notched support, a Bourdon spring having one end fitting in the notch in said support, said end being opened out in section so as to provide enlargements at top and bottom, and capillary tubes fitted into said enlargements.

24C. In instrument construction the combination of a notched support, a Bourdon spring having one end fitted inthe notch in said support and opened out in cross section so as to provide spaced enlargements, and capillary tubes fitted in said enlargements, the end of said Bourdon coil .being secured Within the'notched `support and the ends of said capillary tubes being sealed Within the ends of said Bourdon spring by a illingof Solder in the notch of said support surrounding and embedding therend ofl -said Bourdnnf spring and the adjacent portions` of the capillary tubes.

25. In instrument construction the combination of a Bourdon spring closed at one end and having two capillaryrtubes enterl ing and sealed to the'other end thereof,'

one of said capillary tubes being connected at its opposite end to a bulb andthe other for the part of said Ycapillary tube outside' of said instrument casing, and a leading-inV sleeve having 'a neck portion fitting an opening in the instrument casin Wall and riveted tov said Wall; said leading-,in sleeve having a hole 4therethrough adapted to re-L ceive the end of said casing tube.

27. In instrument construction the combination of a casing having a pressure-responsive element therein,`a capillary tube leading into said casing and connected tol said pressure-responsive element, said capillary tube being protected exteriorly of said casing by a casing tube and a flexible tubular armour, anda leading-in sleeve mountthrough of a diameter toreceive and fit'the end of 'the casing tube, and having an enlarged Ybore in the outer part thereof adaptedito receive the end of the'tubular 28. In instrument construction the combination of a Ycasing having a round hole therein notched out at intervals, a pressureresponsive element in the casing, a capillary tube extending from the outside of said casing through the hole therein into the Y interior of the casing and communicating with said pressure-responsive element, and a leading-in sleeve having a cylindrical neck porf tion fitting in said hole and havin the metal thereof upset into the notches oi said hole so as to secure said sleeve tol the casing Wall. Y

' HERMAN YSCHLAICH. Y

40 ed on the casing 'and' having a hole therei 

